---
layout: docs
page_title: Use redundancy zones
description: >-
  Use redundancy zones with hot standby nodes for improved scalability and
  resiliency with Vault Enterprise clusters.
---

# Use redundancy zones

@include 'alerts/enterprise-only.mdx'

Vault Enterprise redundancy zones provide both read scaling and resiliency benefits by enabling
the deployment of non-voting nodes alongside voting nodes on a per availability zone basis.

When using redundancy zones, if an operator chooses to deploy Vault across three availability zones,
they could have two (or more) nodes (one voting/one+ non-voting) in each zone. In the event that a
voting node in an availability zone fails, the redundancy zone configuration automatically
promotes the non-voting node to a voting node. In the event that an entire availability zone is
lost, a non-voting node in one of the existing availability zones would be promoted to a voting
node, keeping quorum. This capability functions as a "hot standby" for server nodes while also
providing enhanced read scalability.

## Configuration
A new key can be added to Vault's `storage` configuration stanza: `autopilot_redundancy_zone`.
The value for this key is a string of your choosing and represents the zone this particular node
should be in.

## Mechanics
Vault's Autopilot subsystem will always attempt to maintain exactly one voting node per redundancy
zone. Any additional nodes beyond the first one will be demoted to non-voting status. Non-voting
nodes can serve reads but can not participate in cluster elections.

If redundancy zones are used in conjunction with automated upgrades, Autopilot will always try to
ensure that Vault is never moving from a more healthy state to a less healthy state. Autopilot will
wait to begin leadership transfer until it can ensure that there will be as much redundancy on the
new Vault version as there was on the old Vault version.

The status of redundancy zones can be monitored by consulting the [Autopilot state API endpoint](/vault/api-docs/system/storage/raftautopilot#get-cluster-state).

## Optimistic Failure Tolerance

@include 'autopilot/redundancy-zones.mdx'
